1. Field of the Invention
The present invention relates to an X-ray radiographic apparatus and method, and specifically relates to a technique for obtaining one long length of X-ray image by taking plural X-ray images and connecting these X-ray images.
2. Description of the Related Art
In plain X-ray radiography, a long length of image is sometime taken for a region with a long length, such as the entire backbone or the entire legs.
Conventional computed radiography (CR) is X-ray radiography using a storage phosphor sheet (imaging plate: IP) instead of an X-ray film. In the CR, when taking a long length of image, images are taken with IPs overlapped each other, and a long length of image is obtained by combining images read from the respective IPs (Japanese Patent Application Laid-Open No. 2000-232976). Also, in this case, more accurate alignment can be performed by providing markers made of, e.g., lead, in the region where the IPs overlap each other.
Meanwhile, in recent years, for plain X-ray radiography, DR (digital radiography) has been proposed as an improvement from the aforementioned CR method. In the DR, an X-ray is converted into electrical signals and read as they are by means of an X-ray flat panel detector (FPD) with a large area, and long-length imaging using this FPD has also been performed.
Examples of long length imaging methods mainly include: an X-ray tube turning method in which plural images are taken while an X-ray tube is turning (Japanese Patent Application Laid-Open No. 2004-358254); and an X-ray tube parallel movement method in which plural images are taken while an X-ray tube being moved in parallel to itself (Japanese National Publication of International Patent Application No. 2006-500126).